Zoologi/.} NATURAL HISTORY OF VICTORIA. [Po/yzoo. 



Plate 196, Fig. 3. 

 THAIROPOKA JERVOISII (Hincks sp.). 



Description. — ZocBcia larg-e, alternate; calcareous lamina tliick, finely granular 

 or punctate, usually traversed by two prominent raised lines crossing- the zocecia and 

 connected in the centre by a similar vertical line, or by two from one side meeting' 

 about the centre and continued as a single line across the remainder of the zooecium. 

 Mouth large, lofty, oral processes large mamilliform. Avicularian mandible broadly 

 triangular, the lateral branches 'not produced and with a very narrow membranous 

 fringe. 



Reference. — Steganoporella Jervoisii, Hincks, Ann. and Mag. Nat. Hist., 

 1880; Thairopora Jervoisii, MacGillivray, Tr. Roy. Soc. Vict., July, 1886. 



Sorrento, Rev. Dr. Porter. 



Of this species I have only a single Victorian specimen, l)iit 

 I have received several from South Australia. It differs from 

 T. armata and mamillaris in the greater size of the zooecia, 

 the strong hand on the calcareous lamina, and the different 

 structure of the avicularian mandible. The avicularia seem to 

 he very rare and are present on only one of my specimens 

 which I unfortunately did not receive until after the plate was 

 lithographed. As far as I can make out from an examination in 

 situ there is an extremely narrow scarcely perceptible fringe. 

 Almost all the specimens are destitute of the epitheca, but in 

 one it appears in parts as a thin silvery layer. None of my 

 specimens have the lateral foramina described and figured by 

 Mr. Hincks, in consequence of which he referred it to the 

 genus Steganoporella. although he subsequently (Ann. and Mag., 

 1887) mentions it as a Micropora. 



The genus Thairopora as first proposed by me was differen- 

 tiated from Memhranipora by the presence of a complete 

 articulated operculum. Subsequent examination has shown, 

 however, that the front wall is not membranous, but consists 

 of a calcareous layer .covered by a *chitinous epitheca. The 

 calcareous lamina is very thin in T. mamillaris^ but of considerable 

 thickness in the others. In T. mamillaris, armata, and Jervoisii 



[ 352 ] 



